Ensures callback placeholders are tested for and eventually replaced in data only when contentType is application/x-www-form-urlencoded and data is a string. Removes json to jsonp promotion when jsonp or jsonpCallback options are present. Uses new Deferred.always method to bind cleanUp function.

Adds fn.promise as a mean to observe the completion of animations on a set of elements. Only queued animations are handled for now, non-queued animations support coming soon. Effects unit tests updated to test the feature (needs more testing though).